@misc{BonnelMaurerRosert, author = {Bonnel, Jean-Marie and Maurer, Michael and Rosert, Reinhard}, title = {Submerged-arc surfacing of higt-alloy steels by flux-cored wires}, series = {Avtomatičeskaja svarka = Automatic welding}, journal = {Avtomatičeskaja svarka = Automatic welding}, number = {6}, issn = {0005-111X}, doi = {10.15407/as2019.06.01}, pages = {4 -- 13}, abstract = {Cored wires are used in numerous welding processes with or without extern al gas or flux shielding. Submerged are welding (SAW) with eored wires, seamed or seamless, for joining mild and low alloyed steel grades is a technique that has demonstrated clear advantages during the three last decades. Ever since its invention, the SAW process has evolved with one main goal: to combine quality with produetivity. With low alloy wires, the benefits have already been clearly demonstrated and widely exploited. However, little has been written on SA Wand cladding with eored wires for eorrosion or he at resisting applieations. Its extension to high alloy eompositions brings eorresponding benefits and adds so me specific and unique features. This paper foeuses on consumable specificities and on the quality and productivity features of SAW with CRA (corrosion resistant alloy) cored wires. It deseribes the potential as weIl as the limitations ofthis technique. Cored wires are now used for submerged are welding of almost aIl stainless steels ranging from soft martensitic to super-duplex, and for aseries of nickel base compositions as weIl as for cladding cobalt base aIloys. Examples of industrial applications with austenitic, duplex, martensitic and heat resisting stainless steels are given to illustrate the potential ofthe eored wire solution.}, language = {en} } @misc{DoynovStapelfeldMichailovetal., author = {Doynov, Nikolay and Stapelfeld, Christoph and Michailov, Vesselin and Pasternak, Hartmut and Launert, Benjamin}, title = {Distortion analysis of large scaled welded structures}, series = {Mathematical Modelling of Weld Phenomena 12 : selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability : September 23-26, 2018, Graz, Schloss Seggau - Austria}, journal = {Mathematical Modelling of Weld Phenomena 12 : selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability : September 23-26, 2018, Graz, Schloss Seggau - Austria}, editor = {Sommitsch, Christof and Enzinger, Norbert and Mayr, Peter}, publisher = {Verlag der Technischen Universit{\"a}t Graz}, address = {Graz}, isbn = {978-3-85125-615-4}, doi = {10.3217/978-3-85125-615-4}, pages = {254 -- 280}, abstract = {The work presents an innovative approach for simulation of welding induced distortions, which allows taking into consideration the local effects of the welding process as well as the global interactions in the structure. The approach bases on an integration of analytical and numerical calculation's procedures in a hybrid model, realized with the aid of the inherent strain concept. The analytical procedure calculates the shrinkage strain components and area of the plastic deformed zone, caused by welding. The calculated strains are then transferred to the global finite element model in order to predict the distortions and stresses in the structure after every welding stage, as well as their final state. The consideration of welding scenarios, weld sequence, clamping conditions and the assembling stages is done by taking into account the intermediate variation of the strain state during the manufacturing steps. The article gives the theoretical basis of the analytical model. The consideration of the essential physical relations is put into discussion. The application of the model is illustrated on complex structures. Its reliability and practicability are demonstrated by means of a validation study.}, language = {en} } @misc{EvdokimovOssenbrinkDoynovetal., author = {Evdokimov, Anton and Ossenbrink, Ralf and Doynov, Nikolay and Michailov, Vesselin}, title = {Laser beam welding of steel-aluminum joints - influence of weld metal elastic-plastic properties on the distortions}, series = {Mathematical Modelling of Weld Phenomena 12 : selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability : September 23-26, 2018, Graz, Schloss Seggau - Austria}, journal = {Mathematical Modelling of Weld Phenomena 12 : selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability : September 23-26, 2018, Graz, Schloss Seggau - Austria}, editor = {Sommitsch, Christof and Enzinger, Norbert and Mayr, Peter}, publisher = {Verlag der Technischen Universit{\"a}t Graz}, address = {Graz}, isbn = {978-3-85125-615-4}, doi = {10.3217/978-3-85125-615-4}, pages = {431 -- 440}, abstract = {Great attention is focused nowadays on laser welding of dissimilar steel-aluminum joints in overlap configuration in key-hole mode. It was found that elastic-plastic properties of the weld metal exhibit strong difference to those of the base alloys and can be defined as a function of aluminum content in the weld metal. A developed Finite-Element simulation model allows prediction of the aluminum content as a function of welding parameters and subsequently the elastic-plastic properties of the weld metal as a function of the determined content. The main goal of the present study is to show the impact of the weld metal properties on welding distortions and residual stresses. For that purpose, a sensitivity analysis of the thermomechanical model was performed, where the distortions and residual stresses were computed as a function of welding parameters and therefore as a function of corresponding weld metal properties. The analysis showed that the influence of the weld metal is essential, and its properties should be taken into consideration in the models for better prediction accuracy.}, language = {en} } @misc{KaishevaBokuchavaPapushkinetal., author = {Kaisheva, Darina and Bokuchava, Gizo and Papushkin, Igor and Genchev, Gancho Vladimirov and Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin and Petrov, Peter}, title = {Determination of residual stresses in fiber laser welded stainless steel joints by neutron diffraction method}, series = {Proc. SPIE 11047, 20th International Conference and School on Quantum Electronics: Laser Physics and Applications}, journal = {Proc. SPIE 11047, 20th International Conference and School on Quantum Electronics: Laser Physics and Applications}, address = {Nessebar}, doi = {10.1117/12.2516421}, pages = {7}, abstract = {This study presents an experimental results of residual stress states in stainless steel plate samples with size 100 x 50 x 10 mm welded using a high-power fiber laser. The technological parameters of the welding process were: laser power Q = 15 kW; laser spot size = 0.65 mm; welding speed V = 3 m/min; 4 m/min; 5 m/min, using 30 L/min of protective Ar gas. The neutron diffraction method was used to determine the residual stresses in the bulk of the material. The neutron experiments were performed on the FSD diffractometer at the IBR-2 pulsed reactor in the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research - Dubna, Russian Federation. The measured residual stress distributions exhibit maxima at weld seam centers. As expected, for all specimens the residual stress is falling down in regions distant from the weld zone. Maximal residual stress value of 492 MPa was observed for sample welded with speed of V = 5 m/min.}, language = {en} } @misc{NaumovMorozovaRylkovetal., author = {Naumov, Anton and Morozova, Iuliia and Rylkov, Evgenii and Obrosov, Aleksei and Isupov, Fedor and Michailov, Vesselin and Rudskoy, Andrey I.}, title = {Metallurgical and Mechanical Characterization of High-Speed Friction Stir Welded AA 6082-T6 Aluminum Alloy}, series = {Materials}, volume = {12}, journal = {Materials}, number = {24}, issn = {1996-1944}, doi = {10.3390/ma12244211}, pages = {16}, abstract = {The objective of this study was to investigate the effect of the high welding speed on the mechanical properties and their relations to microstructural characteristics of butt friction stir welded joints with the use of 6082-T6 aluminum alloy. The aluminum sheets of 2.0 mm thick were friction stir welded at low (conventional FSW) and high welding speeds (HSFSW) of 200 and 2500 mm/min, respectively. The grain size in the nugget zone (NZ) was decreased; the width of the softened region was narrowed down as well as the lowest microhardness value located in the heat-affected zone (HAZ) was enhanced by HSFSW. The increasing welding speed resulted in the higher ultimate tensile strength and lower elongation, but it had a slight influence on the yield strength. The differences in mechanical properties were explained by analysis of microstructural changes and tensile fracture surfaces of the welded joints, supported by the results of the numerical simulation of the temperature distribution and material flow. The fracture of the conventional FSW joint occurred in the HAZ, the weakest weld region, while all HSFSW joints raptured in the NZ. This demonstrated that both structural characteristics and microhardness distribution influenced the actual fracture locations.}, language = {en} } @misc{WasilewskiKaneneksDoynovetal., author = {Wasilewski, Eric and Kaneneks, Michael and Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Laserstrahlschweißen - Verzugs- und Kaltrissminimierung durch simulationsbasierte Steuerung}, series = {DVD Congress 2020 : Große Schweißtechnische Tagung : DVS Campus : Vortr{\"a}ge der Online-Veranstaltungen vom 14. bis 18. September 2020}, journal = {DVD Congress 2020 : Große Schweißtechnische Tagung : DVS Campus : Vortr{\"a}ge der Online-Veranstaltungen vom 14. bis 18. September 2020}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-098-6}, pages = {9}, abstract = {Leichtbau und das Streben nach Ressourcen- und Energieeffizienz f{\"o}rdern in den letzten Jahren vermehrt den Einsatz hochfester St{\"a}hle. Das Laserstrahlschweißen dieser Werkstoffe wird in der industriellen Großserienferti-gung zur effizienten Herstellung hochpr{\"a}ziser Bauteile und Komponenten mit h{\"o}chsten Qualit{\"a}tsanforderungen eingesetzt. Die Vermeidung schweißbedingter Fehler wie Schweißverzug und Kaltrissbildung sind dabei von ent-scheidender Bedeutung. Konventionelle Anwendungen erf{\"u}llen diesen Anspruch derzeit bedingt durch sehr enge Prozesstoleranzen und die Auswahl unkritischer Werkstoffe, was die Potentiale der F{\"u}geverbindung begrenzt. Auf Basis von FE-Schweißprozesssimulationen konnten Konzepte entwickelt werden, welche eine Verzugs- und Riss-minderung durch aktive Steuerung des Laserschweißprozesses erm{\"o}glichen. Die zugrundeliegenden Modelle be-r{\"u}cksichtigen zum einen das schweißbedingte Temperaturfeld, Gef{\"u}geumwandlungen und Eigenspannungen f{\"u}r die Berechnung des Verzugs. Zudem wird die lokale Wasserstoffkonzentration berechnet und die Ergebnisse der Schweißprozesssimulation mittels eines Kaltrisstools bewertet, welches werkstoffspezifische Risskriterien enth{\"a}lt. Die F{\"a}higkeit das Verzugs- und Kaltrissverhalten abzubilden, er{\"o}ffnet die M{\"o}glichkeit zur Parametervariation. Aus den erhobenen Daten wurden Konzepte der aktiven Krafteinleitung mit einer dynamischen Werkst{\"u}ckeinspannung abgeleitet, die zu Verzugs- und Kaltrissminimierung f{\"u}hren und die Schweißbarkeit hochfester Werkstoffe f{\"o}rdern.}, language = {de} } @misc{MorozovaBonnelRosertetal., author = {Morozova, Iuliia and Bonnel, Jean-Marie and Rosert, Reinhard and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Einfluss der Schweißposition beim MSG-F{\"u}lldrahtschweißen auf die Kerbschlagz{\"a}higkeit von hoch- und niedriglegierten St{\"a}hlen}, series = {DVS Congress 2019Große Schweißtechnische Tagung : DVS-Studentenkongress : Vortr{\"a}ge der Veranstaltungen in D{\"u}sseldorf vom 16. bis 17. September 2019}, journal = {DVS Congress 2019Große Schweißtechnische Tagung : DVS-Studentenkongress : Vortr{\"a}ge der Veranstaltungen in D{\"u}sseldorf vom 16. bis 17. September 2019}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-066-5}, pages = {310 -- 318}, abstract = {Die Schweißposition beeinflusst erheblich die mechanischen Eigenschaften der Schweißnaht, insbesondere die Kerbschlagz{\"a}higkeit. Dies zeigt ein umfassender Vergleich der mechanischen Eigenschaften von Schweißg{\"u}tern, die in der Steigposition (PF) und Wannenlage (PA) ausgef{\"u}hrt wurden. Schweißg{\"u}ter von Kohlenstoff-Mangan-St{\"a}hlen weisen in der PF-Position eine reduzierte Kerbschlagarbeit im Vergleich zur PA-Position auf. Dagegen ist bei austenitischen und Duplexst{\"a}hlen der Einfluss der Schweißposition auf die Kerbschlagarbeit genau entgegengesetzt. Der Vortrag fasst den Einfluss der Schweißpositionen auf die mechanischen Eigenschaften zusammen und liefert eine Erkl{\"a}rung f{\"u}r die gegens{\"a}tzlichen Auswirkungen auf die Kerbschlagz{\"a}higkeit der Schweißg{\"u}ter. Der Schwerpunkt liegt dabei auf hochlegierten F{\"u}lldr{\"a}hten mit einer schnell erstarrenden Schlacke. Die Schlackeneigenschaften, Schweißgutmikrostruktur, Delta-Ferrit-Gehalte f{\"u}r Schweißg{\"u}ter vom Typ Duplexstahl (2209) und von austenitischen Schweißg{\"u}tern (308L) sowie die Auswirkungen der Schweißposition auf die Richtung des Schweißkornwachstums werden erl{\"a}utert. Zum Vergleich werden Kohlenstoff-Mangan-Rutil-F{\"u}lldr{\"a}hte mit schnell erstarrender Schlacke herangezogen.}, language = {de} } @misc{NaumovMorozovaIsupovetal., author = {Naumov, Anton and Morozova, Iuliia and Isupov, Fedor and Golubev, Iurii and Michailov, Vesselin}, title = {Temperature Influence on Microstructure and Properties Evolution of Friction Stir Welded Al-Mg-Si Alloy}, series = {Key Engineering Materials}, volume = {822}, journal = {Key Engineering Materials}, issn = {1662-9795}, doi = {10.4028/www.scientific.net/KEM.822.122}, pages = {122 -- 128}, abstract = {The temperature influence on the microstructure evolution and microhardness of the agehardenable aluminium alloy 6082 T6 during friction stir welding was defined. In order to achieve this aim, the thermocycles calculated using the developed 3D Finite Element Model were physically simulated on the Gleeble-3800 in the points which located in the different zones of the weld. The microstructure in the chosen points after Gleeble testing was investigated as well as the microhardness was measured. The results were consequently compared with the relevant results obtained after friction stir welding. It was shown that the microstructure and microhardness profile are influenced not only by temperature but by deformation. The increase in hardness in different zones after FSW compared to Gleeble testing can be explained by the grain refinement in the nugget zone as well as the hardening precipitate distribution along the weld which can occur more rapidly due to the deformation influence.}, language = {en} } @misc{NaumovIsupovGolubevetal., author = {Naumov, Anton and Isupov, Fedor and Golubev, Iurii and Morozova, Iuliia}, title = {Effect of the temperature of friction stir welding on the microstructure and mechanical properties of welded joints of an Al-Cu-Mg alloy}, series = {Metal Science and Heat Treatment}, volume = {60}, journal = {Metal Science and Heat Treatment}, issn = {1573-8973}, doi = {10.1007/s11041-019-00342-0}, pages = {695 -- 700}, abstract = {Amethod for assessing the effect of the temperature of friction stir welding on the microstructure and mechanical properties of welded joints of aluminum alloy D16AT is suggested. The temperature cycles in different zones of a welded joint are determined by mathematical simulation. The computed temperature cycles are implemented in a Gleeble-3800 system. It is shown that the welding temperature affects little the evolution of the microstructure in different zones of the welded joints of alloy D16AT.}, language = {en} } @misc{ShapovalovKodzhaspirovHantelmannetal., author = {Shapovalov, Oleg and Kodzhaspirov, Georgii and Hantelmann, Cord and Michailov, Vesselin}, title = {Effect of a Welding Method on the Fatigue Strength and Fracture of Foam-Aluminum Sandwiches}, series = {Russian Metallurgy (Metally)}, volume = {Vol. 2019}, journal = {Russian Metallurgy (Metally)}, number = {10}, issn = {0036-0295}, doi = {10.1134/S0036029519100239}, pages = {1063 -- 1066}, abstract = {The influence of argon-arc welding and laser welding on the fatigue properties and the fracture of a foam-aluminum sandwich is studied. Argon-arc-welded samples are found to have the highest fatigue strength.}, language = {en} }